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AF/RF Signal Generator: Which one?

dudmuck said:
Generating a precise and stable RF signal is so cheap these days, especially below 30MHz, such as this:
DDS-60 Kit from the AmQRP

They call it a VFO, but its output frequency is exactly locked to the divide ratio from a crystal.

With something as cheap as a DDS, you can concentrate your money on a quality step attenuator to enable you to do precise receiver sensitivity measurements.
Its also possible to do AM modulation on the RSET pin.
Click to expand...


Direct digital synthesis IS the way to go! I'm working on building a microcontroller for that DDS-60 kit (or possibly stepping up to an AD9854 -- look that one up :D ).

Step away from those cheap generators. They make a really dirty signal. I'd go as low as the WaveTek. some of that HP stuff is OK too, but you gotta be careful as the older stuff tends to have problems and it is not cheap or easy to fix.


If I had the time, I'd have that DDS-60 up and running by now. If you want to control it by PC, it's ready to roll. You'd have to build your own level control and attenuator. And then it is CW only. I was going to make the first build just to replace old VFOs for rig control.
 
BTW, Robb, I have a couple of the generators like you've posted. Maybe that protek and one of the older ones.

Let me digg around...
 
It's not far away now, Robb...


Saturday Mar.13 Flea Market - Hosted by South Peninsula Amateur Radio Klub. First Flea Market for 2010!
 
Do you have an extra radio laying around? Pull the final and and run off the driver (attenuate the output or just run off the driver input).

Build an RF attennuator box with 10 steps of 10 dB each, put a variable on the driver, and a micro-volt meter on the output at the radio.

Now you can modulate the mic input with that free PC tone generator.
 
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Radio Tech said:
Ok then.
Then this is why the generators you mentioned will not do what you need.
About all they can do is adjust RX sensitivity. Not the best either.
You will need to be able to generate a signal that you can attenuate. Throw in a tone at say 30 percent modulation. You may need a 455kz added and a noise generator.

Then there is the transmitter. Yes you can use a watt meter and a frequency counter along with a dummy load. But hey, let’s say you need to check a 2 meter mobile for deviation and frequency error. That’s FM let alone the receiver can not be tested with the old generator.

See the possibilities are endless. Those that mole posted are fine. May sound a bit high. I will say that my IFR was over 9 grand new. Around $1100 to $3500 used.
You should be able to find one that is suitable for around a couple hundred.

Now for another piece I recommend. Someone turned me on to this and it is great.
Look for a Sencore SC-61 scope. That thing is a dream!
60 mhz usable to 100. Has a LCD display.
You can measure voltage peak to peak and direct up to 2000 volts.
And you can measure frequency with a 10X probe.

I got mine on ebay for $149. Last week I had a rig in with not tx. 3 minutes with this scope and the problem was found. Coupling capacitor between the driver and final had shorted.
Sure makes trouble shooting easy.
Click to expand...
Has anyone used this tone download? If so what tone do you use? theres alot of tones.
 

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